Children as young as 12 can begin receiving Pfizer’s COVID-19 vaccine in Colorado starting this week, and Ouray County school districts are hoping to set up mobile vaccination clinics for their eligible students soon.

The U.S. Food and Drug Administration expanded authorization for the Pfizer-BioNTech vaccine to anyone over 12 on Monday, and an advisory committee at the Centers for Disease Control and Prevention agreed on Wednesday, clearing the way for children to begin getting shots.

The autho...